1. Field of the Invention
The present invention relates to a lens-equipped optical waveguide device for a touch panel and a manufacturing method thereof.
2. Description of the Related Art
Touch panels are input devices for operating an apparatus by directly touching a display screen of a liquid crystal display device or the like with a finger, a purpose-built stylus or the like, and include a display which displays operation details and the like, and a detection means which detects the position (coordinates) of a portion of the display screen of the display touched with the finger or the like. Information about the touch position detected by the detection means is sent in the form of a signal to the apparatus, which in turn performs an operation and the like displayed on the touch position. Examples of the apparatus employing such a touch panel include ATMs in banking facilities, ticket vending machines in stations and portable game machines.
A detection means employing an optical waveguide is proposed as the detection means for detecting the finger touch position and the like on the touch panel (see, for example, US 2004/0201579A1). Specifically, the touch panel includes optical waveguides provided around a periphery of a display screen of a rectangular display, and is configured to emit a multiplicity of light beams parallel to the display screen of the display from an optical waveguide provided on one side portion of the display screen toward the other side portion, and to receive the light beams with an optical waveguide provided on the other side portion. The optical waveguides cause the light beams to travel in a lattice on the display screen of the display. When a portion of the display screen of the display is touched with a finger in this state, the finger blocks some of the light beams. Therefore, the optical waveguide which receives the light beams senses a light blocked portion, whereby the position of the portion touched with the finger is detected.
The light beams emitted from an optical waveguide directly into the air diverge radially. In this state, light transmission efficiency is low. To enhance the light transmission efficiency, a lens-equipped optical waveguide device is proposed in which a lens is placed at the front of an optical waveguide which emits light beams to thereby prevent the light beams from diverging, and another lens is similarly placed at the front of an optical waveguide which receives the light beams to thereby cause the light beams in a converged state to enter the optical waveguide. This lens-equipped optical waveguide device is shown in FIGS. 10(a) and (b). In FIGS. 10(a) and (b), the lens-equipped optical waveguide device includes a lens device 20 and an optical waveguide 10. The lens device 20 includes a mounting surface 21 for placing the optical waveguide 10 thereon, and a lens 22 formed to protrude from one edge portion of the mounting surface 21. The optical waveguide 10 is placed on the mounting surface 21 of the lens device 20 and is positioned so that light beams pass through the lens 22. The refraction of the lens 22 is used to prevent the divergence of light beams emitted from the optical waveguide 10 and to converge incident light beams entering a light-receiving optical waveguide 10 in a manner described above.
The manufacture of the above-mentioned lens-equipped optical waveguide device is accomplished by applying an adhesive onto the mounting surface 21 of the lens device 20, placing the optical waveguide 10 on a coating layer 30 of the adhesive to press down the optical waveguides 10, and then hardening the coating layer 30 of the adhesive, thereby bonding and fixing the optical waveguide 10 to the above-mentioned mounting surface 21.
In the above-mentioned lens-equipped optical waveguide device, however, the optical waveguide 10 is placed on the coating layer 30 of the adhesive and pressed down after the adhesive is applied. This causes the adhesive to be squeezed out of a peripheral edge of the optical waveguide 10 to deface a peripheral portion of the optical waveguide 10. Additionally, unevenness in the thickness of the coating layer 30 of the adhesive complicates alignment (in particular, alignment in the heightwise direction) between the optical waveguide 10 and the lens 22.